Electric switch



Dec. 27, 1938. sCHAEFE-R 7 2,141,227

ELECTRIC SWITCH Filed Sept. 18, 1956 5 Sheets-Sheet l IN VENTOR Carl fZ 5622467592:-

3Y7? ar Dec. 27, 1938. c, A, SCHAEFER 2,141,227

ELECTRIC SWITCH Filed Sept. 18, 1936 3 Sheets-Sheet 2 INVENTOR ('drZ' 17, 56%48/671 BY W ZTT ORNEV Dec. 27, 1938. Q A, SCH'AEFER 2,141,227

ELECTRIC SWITCH IN VENTOR far! /7. 56%46787? Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE ELECTRIC SWITCH tion of Michigan Application September 18, 1936, Serial No. 101,367

8 Claims.

This invention relates to electric switches and more particularly to electric switches automatically operable in response to variations in external conditions.

In the operation of automatic electric switches such as electric switches responsive to pressure or temperature, the operation of the mechanism in opening and closing the circuit through the switch will be effected at a predetermined differential of variation in the external condition. In the operation of systems employing such switches it often becomes desirable either to maintain the contacts in one position regardless of the condition or to anticipate the action of the switch by moving the contacts to another position while the pressure condition is within the limits of differential.

One object of the present invention is the provision in an automatic switch of means for manually moving the contacts at will either momentarily or relatively permanently;

Another object of the invention is to provide an electric switch automatically operable in response to variations in an external condition with means for closing the contacts independently of the condition.

Another object of the invention is to provide an electric switch responsive to pressure or other external condition and having protective devices for opening the contacts with means for effecting closing of the contacts either momentarily or relatively permanently without disabling the action of theprotective devices in opening the contacts in response to predetermined maximum conditions.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and appended drawings illustrating certain preferred embodiments of the invention in which:

Figure 1 is a front elevational view of an electric switch according to the present invention.

Figure 2 is an enlarged front elevational view similar to Figure 1 with the cover removed and certain parts shown in section.

Figure 3 is a horizontal sectional viewon the line III-III of Figure 2.

Figure 4 is a front elevational view on the line IV-IV of Figure 3 with certain parts broken away and with a manual operator moved to a. stable position to effect relatively permanent closing of the contacts.

Figure 5 is a detailed sectional view on the line V--V of Figure 4.

Figure 6 is a detailed view showing the action Serial No. 77,723, filed May 4, 1936 for Electric switches. This switch comprises an insulating enclosure l having a front cover 2 carrying a manual actuator 3 for moving the contacts to the off position and for resetting a thermal overload relay to be hereinafter described. For actuating the switch there is provided a normal pressure responsive assembly generally indicated at 4 and the switch is provided with a further protective device comprising a high pressure responsive cut-out indicated generally at 5.

Within the enclosure I is mounted a conducting bracket 6 having a pair of arms I and 8 pivoted thereon by trunnion ended studs I0. The arm 8 is a conducting arm carrying contact surface 9 thereon at the forward side of the arm "I which contact surface is headed or otherwise re stricted in its movement with respect to the arm I. A stationary contact 2 2 is mounted on a resilient arm I3 and a cam I4 is provided for adjusting the position of the stationary contact I2 and hence the air gap between the magnetic arm I and the permanent magnet I I. A light tension spring l5 biases the contact arms into engaged position. For moving the contact surface 9 to the disengaged position a pin I6 is mounted on the arm I and is adapted to be engaged by an insulating portion I! on a lever I8 pivoted toa fixed part as at 20. A compression spring I9 biases the lever I8 downwardly and is provided with an adjusting screw 2I for adjusting the range of operation of the device. The normal pressure responsive unit comprises a chamber 22 having a bellows unit and is adapted to press against the under side of the lever I8. A spring 25 is adapted to be adjusted by a knurled nut 26 which may be provided for varying the limits of the range variation of the device.

The high pressure cutout protective unit comprises a bellow chamber 28 having a bellows 21 therein connected to a pin 29 adapted to engage a toggle formed by a pivoted link 3| and a compression spring 30 engageable therewith. A compression spring 33 having an adjusting nut 34 may be provided for varying the range of operation of the high pressure cutout. Above the link 3| is a rectilinearly movable pin 35 provided with a biasing spring 32 and in the pathof pin 35 is disposed a pivoted lever 38 arranged to strike the contact arms when moved by the pin and normally biased away from the contact arm by a torsion spring 50. Upon movement of the toggle formed by the link 3| and spring 30 over center through the force supplied by the pin 29 the toggle will move the pin 35 into engagement with the pivoted lever 36 and cause it to strike the contact arms and move them to the off position. Upon a reduction in the pressure to which the high pressure cutout is connected the toggle will snap in the reverse direction and will again place the control of the contact arm in the normal operating mechanism.

A second protective device for the switch comprises an overload relay including an insulating piece 3'! having mounted thereon a ratchet wheel 38 held against movement by solidified metal within a cylinder 39. A resistance coil 4| is wrapped around the cylinder 39 for heating and melting this metal upon the occurrence of an overload to permit the ratchet wheel 38 to turn. A rectilinearly movable slide 42 is biased toward the right as shown by a tension spring 43 and is held in position by engagement ,with the teeth on the ratchet wheel 38. In back of the block 3! the slide is provided with a striker 44 adapted to engage an extension 40 on the arm 1 to move the contact surface to disengaged position upon the occurrence of an overload. For resetting the thermal unit there is provided a pivoted element 45 having a. resetting arm 46 adapted to engage the slide 42 and move it back into latching position upon rotation of the element. The element 45 is rigidly secured to a shaft 41 having a tongue and slot removable connection with the external operator 3. An over center spring and guide 48 may be connected to the element 45 to render its movement snap-like in action. At the back of the block 31 the shaft 45 may be rigidly connected to a second striker, not shown, for holding the contacts open during resetting and for normally moving the contacts to the ofl position, all as more fully described and claimed in the aforesaid co-pending application.

According to the present invention there is provided an elongated pin guided for rectilinear movement by openings at the top and bottom of the enclosure Near the bottom of the enclosure the pin 5| is provided with a force applying means shown as a washer 52 mounted on the pin as by means of a cotter pin 53. On the top of the enclosure is provided a metallic plate 54 and cooperating with this plate is a manually manipulable member 55 pivotally connected to the upper end of pin 5| as by -otter pin 56. A compression spring 57 is suitably interposed between a stationary-part and a pin 58 on the pin 5| and biases the pin 5| downwardly. The manual operator 55 is provided with two operating portions constituted by a stable portion 59 and a momentary rocking portion 5|.

The omration of the switch will now be described:

The parts as shown in Figure 2 are under the control of the automatic mechanism and the contacts have been separated by a decrease in pressure within the bellows chamber 22. Upon an increase in pressure within this chamber the lever |8 will be moved upwardly through the influence of bellows pin 24 and the contact surface 9 will be moved into engaged position under the bias of the spring l5. Due to the rapidly increasing force of the magnet H as the arm 1 moves toward engaged position the contacts will close with a snap action. Similarly upon decrease in pressure within the chamber 22 the spring I! will move the lever l8 downwardly and the contacts will be separated by the engagement of the insulating portion H with pin IE on the lever l. The contact surface 9 will be moved to the open position with a snap action due to the rapid decrease in the force exerted by the magnet With the parts as shown in Figure 2, it is apparent that the pressure condition within the chamber 22 is within the difierential of operation of the switch. Should it be desired to close the contacts before the pressure condition reaches its lower limit the manual operator 55 is depressed, as shown in Figure 6, and rocks about the pivot point 6| to move the pin 5| upwardly. This moves the lever I5 upwardly against the bias of the range spring l9 and permits the contact arms to be moved to their engaged position under the bias of the spring I5. This depression of the manual operator 55 need be only momentary as once the contacts are closed they will remain closed until the pressure condition within the bellows chamber 22 reaches the upper limit of the diil'erential.

Should it be desired to effect a relatively permanent continuous operation the manual operator 55 is moved upwardly as shown in Figure 4, thus again moving the pin 5| upwardly and holding it there as this constitutes a stable position with the portion 59 engaging with the plate 54.

One very important feature of the present invention lies in the fact that with the contacts closed through the influence of the manual operator either momentarily or relatively permanently it is seen that the contacts are held engaged only by the bias of the spring l5 and the force exerted by the magnet Hence, both the current responsive overload relay and the high pressure cut-out are operable to open the contacts upon the attainment of an overload or a predetermined maximum pressure. This permits manual operation of the switch to eilect closing the contacts irrespective of the normal pressure condition without disabling the protective action of the overload relay and/or the high pressure cut-out.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims:

What is claimed is:

1. An electric switch comprising stationary and movable contacts, means including a fluid pressure responsive element for normally moving said movable contact to engaged and disengaged position in response to an exterior condition, protective means for moving said movable contact to disengaged position in response to an abnormal condition, and means for moving said movable contact to engaged position at will irrespective of said first condition but without disabling the action of said protective means in moving the movable contact to disengaged position in response to the abnormal condition.

2. An electric switch comprising stationary and movable contacts, means including a fluid pressure responsive element for normally moving said movable contact to engaged and disengaged positions in response to an exterior condition, current responsive means for moving said movable contact to disengaged position in response to a current overload through the switch, a high pressure cut-out for moving said movable contact to disengaged position in response to a predetermined condition, and manual means for moving said movable contact to engaged position irrespective of said first condition but without disabling the actions of said current responsive means and high pressure cutout in moving the movable contact to disengaged position in response to current overload and the attainment of said maximum pressure.

3. An electric switch comprising stationary and movable contacts, means including a fluid pressure responsive element for normally moving said movable contact to engaged and disengaged positions in response to an exterior condition, current responsive means for moving said movable contact to disengaged position in response to a current overload through the switch and manual means for moving said movable contact to engaged position irrespective of said first condition but without disabling the action of said current responsive means in moving the movable contact to disengaged position in response to current overload.

4. An electric switch comprising stationary and movable contacts, means including a fluid pressure responsive element for normally moving said movable contact to engaged and disengaged positions in response to an exterior condition, a high pressure cutout for moving said movable contact to disengaged position in response to a predetermined maximum pressure condition, and manual means for moving said movable contact to engaged position irrespective of said first condition but without disabling the action of said high pressure cutout in moving the movable contact to disengaged position in response to the attainment of said maximum pressure.

5. An electric switch comprising separable contacts biased to engaged position, normal means for automatically separating said contacts in response to an exterior condition, protective means abnormally operable to separate said contacts in response to a predetermined maximum condition, and means for disabling the operation of said normal means in separating said contacts without hindering the operation of said protective means.

6. An electric switch comprising stationary and movable contacts, means biasing said movable contact to engaged position, a plurality of means for automatically moving said movable contact to separated position against said biasing means, and manual means for disabling the action of one of said means in moving the movable contact to separated position so as to maintain the contacts engaged independent of said one of said means, but without hindering the operation of the remaining means in moving the movable contact to separated position.

7. An electric switch comprising separable contacts, normal means for automatically effecting engagement and separation of said contacts in response to a certain condition, protective means abnormally operable to effect separation of said contacts in response to a predetermined maximum condition, and means for effecting engagement of said contacts at will irrespective of said first condition but without hindering the operation of said protective means to efiect separation of the contacts.

8. An electric switch comprising separable contacts, means including a pressure responsive element for normally effecting engagement and separation of said contacts in response to an exterior condition, protective means for efiecting separation of said contacts in response to an abnormal condition, and means for effecting engagement of said contacts at will irrespective of said first condition but without disabling the action of said protective means in effecting separation of said contacts in response to the abnormal condition.

CARL A. SCHAEFER. 

